"Treetop Trail" Lets Philadelphia Zoo Primates Go Exploring

Forget the old way of building a zoo, where animals are cloistered in cages. The Philadelphia Zoo just opened a new system of elevated steel mesh trails that lets monkeys and lemurs explore the environment around them—and human visitors to get a closer look at primates.

Venturing Out

Venturing Out

In most zoos, it's the human visitors who get to travel freely, exploring the different areas and exhibits while the animals stay confined to their living spaces. At the Philadelphia Zoo, that old-fashioned approach is starting to change. A new project called the Treetop Trail, which opened July 28, is an experiment in the way a zoo is set up, allowing primates to venture out from their home.

The Trail

The Trail

The trail is network of more than 700 feet of tunnels made of flexible stainless-steel mesh, with steel rings installed every few feet to support the weight of the monkeys and the mesh. Treetop Trail's design, construction and modifications cost a total of $1.5 million, which was partially funded by a number of partnerships, but it is the realization of a long-held vision to get animals out of their dens and moving around.